Performance of ZnO/chitosan nanocomposite films for antimicrobial packaging applications as a function of NaOH treatment and glycerol/PVOH blending

The current study investigates the performance of chitosan-based ZnO nanocomposite films for antimicrobial packaging applications. ZnO nanoparticles are fabricated from zinc acetate solutions and added in plain chitosan and chitosan/glycerol-, chitosan/poly(vinyl alcohol)- blends at 3, 5 and 7 wt. %. Characteristic diffraction peaks at 31.6 degrees, 34.3 degrees and 36.2 degrees confirm the successful formation and growth of ZnO nanoparticles in chitosan-based films after their immersion in hot NaOH solution. Poly(vinyl alcohol) supports the growth of ZnO in chitosan chains and results in higher strain at break and increased barrier. The antimicrobial activity of the nanocomposite films is high against Brevibacterium lactofermentum, moderate against Escherichia coli and almost absent against Corynobacterium glutamicum. Positive synergies between chitosan-based matrices and ZnO nanoparticles are not however established in terms of antimicrobial properties due to the immersion of the films in NaOH solution which lowers the polycationic character and the solubility of chitosan.